Surface-enhanced raman scattering unit and raman spectroscopic analysis method

ABSTRACT

A SERS unit  1 A comprises a SERS element  2  having a substrate and an optical function part  20  formed on the substrate, the optical function part  20  for generating surface-enhanced Raman scattering; a measurement board  3  supporting the SERS element  2  upon measurement; and a holding part  4  mechanically holding the SERS element  2  in the measurement board  3.

TECHNICAL FIELD

The present invention relates to a surface-enhanced Raman scatteringunit and a Raman spectroscopic analysis method.

BACKGROUND ART

Known as a conventional surface-enhanced Raman scattering unit is one inwhich a surface-enhanced Raman scattering element having an opticalfunction part for generating surface-enhanced Raman scattering (SERS) issecured onto a glass slide (see, for example, Non Patent Literature 1).

CITATION LIST Non Patent Literature

-   Non Patent Literature 1: “Q-SERS™ G1 Substrate”, [online], Opto    Science, Inc., [retrieved on Mar. 21, 2013]. Retrieved from the    Internet:    <URL:http://www.optoscience.com/maker/nanova/pdf/Q-SERS_G1.pdf>.

SUMMARY OF INVENTION Technical Problem

In a surface-enhanced Raman scattering unit such as the one mentionedabove, the surface-enhanced Raman scattering element is secured onto theglass slide with an adhesive, whereby the optical function part maydeteriorate because of ingredients contained in the adhesive.

It is therefore an object of the present invention to provide asurface-enhanced Raman scattering unit which can inhibit the opticalfunction part from deteriorating and a Raman spectroscopic analysismethod using such a surface-enhanced Raman scattering unit.

Solution to Problem

The surface-enhanced Raman scattering unit in accordance with one aspectof the present invention comprises a surface-enhanced Raman scatteringelement having a substrate and an optical function part formed on thesubstrate, the optical function part for generating surface-enhancedRaman scattering; a measurement board supporting the surface-enhancedRaman scattering element upon measurement; and a holding partmechanically holding the surface-enhanced Raman scattering element inthe measurement board.

In this surface-enhanced Raman scattering unit, the holding partmechanically holds the surface-enhanced Raman scattering element in themeasurement board. If the surface-enhanced Raman scattering element issecured to the measurement board with an adhesive, for example,deterioration will progress in the optical function part because ofingredients contained in the adhesive when the adhesive cures, duringpacking and storage, and upon measurement. However, the surface-enhancedRaman scattering unit in accordance with one aspect of the presentinvention uses no adhesive and thus can inhibit the optical functionpart from deteriorating.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the holding part may have a pinchingpart pinching the surface-enhanced Raman scattering element incooperation with the measurement board. This structure can securely holdthe surface-enhanced Raman scattering element in the measurement board.This can also prevent conductor layers and the like formed on thesubstrate in the surface-enhanced Raman scattering element from peelingfrom the substrate.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the pinching part may be formed into aring so as to surround the optical function part when seen in athickness direction of the substrate, or a plurality of pinching partsmay be arranged around the optical function part. These structures canstably hold the surface-enhanced Raman scattering element in themeasurement board. When bringing the pinching part into contact with apredetermined part of a Raman spectroscopic analyzer in the case ofperforming Raman spectroscopic analysis, the pinching part can beutilized as a spacer for placing a focal point of excitation light atthe optical function part. When the pinching part is formed into a ringso as to surround the optical function part, a region on the inside ofthe pinching part can be utilized as a cell (chamber) for a solutionsample.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the measurement board may be providedwith a depression containing at least a part of the surface-enhancedRaman scattering element on the substrate side and restraining thesurface-enhanced Raman scattering element from moving in a directionperpendicular to the thickness direction of the substrate. Thisstructure can position the surface-enhanced Raman scattering elementwith respect to the measurement board. This can also prevent thesurface-enhanced Raman scattering element from shifting from themeasurement board.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the holding part may be formedseparately from the measurement board and mechanically secured to themeasurement board. This structure can simplify the structure of themeasurement board. In addition, as compared with the case where theholding part is secured to the measurement board with an adhesive, forexample, the optical function part can be more inhibited fromdeteriorating because of ingredients contained in the adhesive.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the holding part may be formedintegrally with the measurement board. This structure can reduce thenumber of components in the surface-enhanced Raman scattering unit. Inaddition, as compared with the case where the holding part is secured tothe measurement board with an adhesive, for example, the opticalfunction part can be more inhibited from deteriorating because ofingredients contained in the adhesive.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the measurement board may be formedintegrally from a resin. This makes it harder for chipping to occur andthus can securely inhibit the optical function part from deterioratingbecause of chipped pieces adhering thereto.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the measurement board may be providedwith a hollowed part so as to form a wall part extending in a directionperpendicular to a thickness direction of the measurement board. Thisstructure prevents the measurement board from warping and thus canaccurately place a focal point of excitation light at the opticalfunction part when arranging the measurement board on a stage of a Ramanspectroscopic analyzer in the case where Raman spectroscopic analysis isperformed.

In the surface-enhanced Raman scattering unit in accordance with oneaspect of the present invention, the holding part may pinch a side faceof the surface-enhanced Raman scattering element.

A Raman spectroscopic analysis method in accordance with one aspect ofthe present invention comprises a first step of preparing theabove-mentioned surface-enhanced Raman scattering unit and arranging asample on the optical function part; and a second step, after the firststep, of setting the surface-enhanced Raman scattering unit to a Ramanspectroscopic analyzer, irradiating the sample arranged on the opticalfunction part with excitation light, and detecting Raman-scattered lightderived from the sample, so as to perform Raman spectroscopic analysis.

This Raman spectroscopic analysis method uses the above-mentionedsurface-enhanced Raman scattering unit and thus can accurately performRaman spectroscopic analysis.

Advantageous Effects of Invention

The present invention can provide a surface-enhanced Raman scatteringunit which can inhibit the optical function part from deteriorating anda Raman spectroscopic analysis method using such a surface-enhancedRaman scattering unit.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of the surface-enhanced Raman scattering unit inaccordance with a first embodiment of the present invention;

FIG. 2 is a sectional view of the surface-enhanced Raman scattering unittaken along the line II-II of FIG. 1;

FIG. 3 is a bottom view of the surface-enhanced Raman scattering unit ofFIG. 1;

FIG. 4 is a partly enlarged sectional view of the surface-enhanced Ramanscattering unit taken along the line II-II of FIG. 1;

FIG. 5 is a SEM photograph of an optical function part in thesurface-enhanced Raman scattering unit of FIG. 1;

FIG. 6 is a structural diagram of a Raman spectroscopic analyzer towhich the surface-enhanced Raman scattering unit of FIG. 1 is set;

FIG. 7 is a partly enlarged plan view of modified examples of thesurface-enhanced Raman scattering unit of FIG. 1;

FIG. 8 is a partly enlarged sectional view of a modified example of thesurface-enhanced Raman scattering unit of FIG. 1;

FIG. 9 is a set of partly enlarged plan and sectional views of amodified example of the surface-enhanced Raman scattering unit of FIG.1;

FIG. 10 is a plan view of the surface-enhanced Raman scattering unit inaccordance with a second embodiment of the present invention;

FIG. 11 is a sectional view of the surface-enhanced Raman scatteringunit taken along the line XI-XI of FIG. 10;

FIG. 12 is a structural diagram of a Raman spectroscopic analyzer towhich the surface-enhanced Raman scattering unit of FIG. 10 is set;

FIG. 13 is a partly enlarged sectional view of modified examples of thesurface-enhanced Raman scattering unit of FIG. 10;

FIG. 14 is a partly enlarged sectional view of modified examples of thesurface-enhanced Raman scattering unit of FIG. 10;

FIG. 15 is a set of partly enlarged plan and sectional views of amodified example of the surface-enhanced Raman scattering unit of FIG.10;

FIG. 16 is a set of partly enlarged plan and sectional views of amodified example of the surface-enhanced Raman scattering unit of FIG.10;

FIG. 17 is a partly enlarged plan view of a modified example of thesurface-enhanced Raman scattering unit of FIG. 10;

FIG. 18 is a partly enlarged sectional view of the surface-enhancedRaman scattering unit in accordance with a third embodiment of thepresent invention;

FIG. 19 is a partly enlarged sectional view of a modified example of thesurface-enhanced Raman scattering unit of FIG. 18;

FIG. 20 is a partly enlarged sectional view of a modified example of thesurface-enhanced Raman scattering unit of FIG. 18;

FIG. 21 is a partly enlarged sectional view of a modified example of thesurface-enhanced Raman scattering unit of FIG. 18;

FIG. 22 is a partly enlarged plan view of the surface-enhanced Ramanscattering unit in accordance with another embodiment of the presentinvention; and

FIG. 23 is a perspective view of the surface-enhanced Raman scatteringunit in accordance with still another embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

In the following, preferred embodiments of the present invention will beexplained in detail with reference to the drawings. In the drawings, thesame or equivalent constituents will be referred to with the same signswhile omitting their overlapping descriptions.

First Embodiment

As illustrated in FIGS. 1 and 2, a SERS unit (surface-enhanced Ramanscattering unit) 1A comprises a SERS element (surface-enhanced Ramanscattering element) 2, a measurement board 3 supporting the SERS element2 upon measurement, and a holding member 4 mechanically holding the SERSelement 2 in the measurement board 3. By “mechanically” is meant“through fitting between members without adhesives and the like.”

The measurement board 3 has a front face 3 a provided with a depression5 containing the SERS element 2 and holding part 4. On the other hand,as illustrated in FIG. 3, the measurement board 3 has a rear face 3 bprovided with a plurality of hollowed parts 8 so as to form wall parts6, 7 extending in directions perpendicular to the thickness direction ofthe measurement board 3. For example, the wall part 6 is formed like aring along outer edges of the measurement board 3, while the wall part 7is formed like grids on the inside of the wall part 6. For example, themeasurement board 3 is formed into a rectangular plate. The depression 5and hollowed parts 8 are formed into rectangular parallelepipeds. Themeasurement board 3 is integrally formed from materials such as resins(polypropylene, styrol resin, ABS resin, polyethylene, PET, PMMA,silicone, liquid crystal polymer, etc.), ceramics, glass, and silicon byusing techniques such as molding, cutting, and etching.

As illustrated in FIG. 4, the SERS element 2 comprises a substrate 21, amolded layer 22 formed on the substrate 21, and a conductor layer 23formed on the molded layer 22. For example, the substrate 21 is formedfrom silicon, glass, or the like into a rectangular plate having anouter form on the order of several hundred μm×several hundred μm toseveral ten mm×several ten mm and a thickness on the order of 100 μm to2 mm.

The molded layer 22 has a fine structure part 24, a support part 25, anda frame part 26. The fine structure part 24, which is a region having aperiodic pattern, is formed on a surface layer opposite from thesubstrate 21 at a center part of the molded layer 22. As the periodicpattern, a plurality of pillars each having a thickness and height onthe order of several nm to several hundred nm are periodically arrangedat a pitch on the order of several ten nm to several hundred nm in thefine structure part 24. The support part 25, which is a regionsupporting the fine structure part 24, is formed on a front face 21 a ofthe substrate 21. The frame part 26, which is a ring-shaped regionsurrounding the support part 25, is formed on the front face 21 a of thesubstrate 21.

For example, the fine structure part 24 has a rectangular outer form onthe order of several hundred μm×several hundred μm to several tenmm×several ten mm when seen from one side in the thickness direction ofthe measurement board 3. The support part 25 and frame part 26 have athickness on the order of several ten nm to several ten μm. The moldedlayer 22 is integrally formed by molding a resin (examples of whichinclude resins based on acrylics, fluorine, epoxy, silicone, andurethane, PET, polycarbonate, and inorganic/organic hybrid materials) orlow-melting glass arranged on the substrate 21 by nanoimprinting, forexample.

The conductor layer 23 is formed over the fine structure part 24 to theframe part 26. In the fine structure part 24, the conductor layer 23reaches a surface of the support part 25, exposed to the side oppositefrom the substrate 21. For example, the conductor layer 23 has athickness on the order of several nm to several μm. The conductor layer23 is formed by vapor-depositing a conductor such as a metal (Au, Ag,Al, Cu, Pt, or the like) on the molded layer 22 molded bynanoimprinting, for example.

In the SERS element 2, the conductor layer 23 formed over the surface ofthe fine structure part 24 and the surface of the support part 25exposed to the side opposite from the substrate 21 produces an opticalfunction part 20, which generates surface-enhanced Raman scattering, onthe substrate 21. For reference, a SEM photograph of the opticalfunction part 20 is illustrated. The optical function part illustratedin FIG. 5 is one in which Au is vapor-deposited as a conductor layer soas to have a thickness of 50 nm on a fine structure part made of ananoimprint resin having a plurality of pillars (each having a diameterof 120 nm and a height of 180 nm) periodically arranged at apredetermined pitch (a distance of 360 nm between center lines).

As illustrated in FIG. 4, the depression 5 has a bottom face 5 aprovided with a depression 9 containing a part of the SERS element 2 onthe substrate 21 side. The depression 9 is formed complementary to apart of the SERS element 2 on the substrate 21 side and restrains theSERS element 2 from moving in directions perpendicular to the thicknessdirection of the substrate 21. The SERS element 2 is not secured to theinner surface of the depression 9 with an adhesive or the like, but isonly in contact with the inner surface of the depression 9.

The holding part 4 has a pinching part 41 formed into a ring so as tosurround the optical function part 20 when seen in the thicknessdirection of the substrate 21 and a plurality of leg parts 42 extendingfrom the pinching part 41 toward the rear face 3 b of the measurementboard 3. Fitting holes 11 are formed in the bottom face 5 a of thedepression 5 so as to correspond to the leg parts 42, respectively. Theleg parts 42 are fitted into their corresponding fitting holes 11 in astate where the pinching part 41 surrounds the optical function part 20and is in contact with the conductor layer 23 of the SERS element 2.Thus, the holding part 4 formed separately from the measurement board 3is mechanically secured to the measurement board 3, while the SERSelement 2 arranged in the depression 9 is pinched by the measurementboard 3 and the pinching part 41 of the holding part 4. As aconsequence, the SERS element 2 is mechanically held with respect to themeasurement board 3. The fitting holes 11 do not penetrate through themeasurement board 3 but are bottomed.

For example, the pinching part 41 is formed such as to have arectangular outer edge and a circular inner edge when seen in thethickness direction of the substrate 21, while the leg parts 42 extendfrom four corners of the pinching part 41, respectively, toward the rearface 3 b of the measurement board 3. Making the inner edge of thepinching part 41 circular prevents pressures from acting locally on theSERS element 2. The leg parts 42 and fitting holes 11 are formedcylindrical. The holding part 4 having the pinching part 41 and legparts 42 is integrally formed from materials such as resins(polypropylene, styrol resin, ABS resin, polyethylene, PET, PMMA,silicone, liquid crystal polymer, etc.), ceramics, glass, and silicon byusing techniques such as molding, cutting, and etching.

The SERS unit 1A further comprises a cover 12 which transmits lighttherethrough. The cover 12 is arranged at a widened part 13 provided inan opening part of the depression 5 and covers the opening part of thedepression 5. The widened part 13 is formed complementary to the cover12 and restrains the cover 12 from moving in directions perpendicular tothe thickness direction of the cover 12. The pinching part 41 of theholding part 4 has a front face 41 a substantially flush with a bottomface 13 a of the widened part 13. As a consequence, the cover 12 issupported not only by the measurement board 3 but also by the holdingpart 4. For example, the cover 12 is formed from glass or the like intoa rectangular plate having an outer form on the order of 18 mm×18 mm anda thickness on the order of 0.15 mm. Until the SERS unit 1A is used, atemporary securing film 14 is attached to the measurement board 3 so asto overlie the cover 12, whereby the cover 12 is prevented from droppingout of the measurement board 3.

A Raman spectroscopic analysis method using the SERS unit 1A will now beexplained. Here, as illustrated in FIG. 6, the Raman spectroscopicanalysis method is performed in a Raman spectroscopic analyzer 50comprising a stage 51 supporting the SERS unit 1A, a light source 52 foremitting excitation light, an optical component 53 for effectingcollimation, filtering, condensing, and the like necessary forirradiating the optical function part 20 with the excitation light, anoptical component 54 for effecting collimation, filtering, and the likenecessary for guiding Raman-scattered light to a detector 55, and thedetector 55 for detecting the Raman-scattered light.

First, the SERS unit 1A is prepared, the temporary securing film 14 ispeeled off from the measurement board 3, and the cover 12 is removedfrom the measurement board 3. Then, a solution sample (or a dispersionof a powder sample in water or in a solution of ethanol) is dropped to aregion on the inside of the pinching part 41 of the holding part 4, soas to be arranged on the optical function part 20 (first step).Subsequently, for reducing the lens effect, the cover 12 is arranged onthe widened part 13 of the measurement board 3, so as to come into closecontact with the solution sample.

Thereafter, the measurement board 3 is arranged on the stage 51, and theSERS unit 1A is set to the Raman spectroscopic analyzer 50.Subsequently, the solution sample arranged on the optical function part20 is irradiated with the excitation light emitted through the opticalcomponent 53 from the light source 52. At this time, the stage 51 ismoved such that a focal point of the excitation light is located at theoptical function part 20. This causes surface-enhanced Raman scatteringat the interface between the optical function part 20 and the solutionsample, whereby Raman-scattered light derived from the solution sampleis released after being enhanced by about 10⁸ times, for example. Thereleased Raman-scattered light is detected by the detector 55 throughthe optical component 54, so as to perform Raman spectroscopic analysis(second step).

Not only the above-mentioned method but the following methods may alsobe used for arranging the sample on the optical function part 20. Forexample, the measurement board 3 may be held, so as to dip the SERSelement 2 into a solution sample (or a dispersion of a powder sample inwater or in a solution of ethanol or the like), lift it up, and thenblow it to dry. A minute amount of a solution sample (or a dispersion ofa powder sample in water or in a solution of ethanol or the like) may bedropped on the optical function part 20 and left to dry. A powder samplemay be dispersed as it is on the optical function part 20.

Effects exhibited by the SERS unit 1A will now be explained. In the SERSunit 1A, the holding part 4 mechanically holds the SERS element 2 in themeasurement board 3. Consequently, as compared with a case where theSERS element 2 is secured to the measurement board 3 with an adhesive,for example, the optical function part 20 is more inhibited fromdeteriorating because of ingredients contained in the adhesive.Therefore, the SERS unit 1A can restrain the optical function part 20from deteriorating. As a result, the Raman spectroscopic analysis methodusing the SERS unit 1A can perform Raman analysis accurately.

In the SERS unit 1A, the holding part 4 has the pinching part 41pinching the SERS element 2 in cooperation with the measurement board 3.This can securely hold the SERS element 2 in the measurement board 3.This can also prevent the molded layer 22 and conductor layer 23 formedon the substrate 21 in the SERS element 2 from peeling from thesubstrate 21.

In the SERS unit 1A, the pinching part 41 is formed into a ring so as tosurround the optical function part 20 when seen in the thicknessdirection of the substrate 21. This can stably hold the SERS element 2in the measurement board 3. Further, a region on the inside of thepinching part 41 can be utilized as a cell (chamber) for a solutionsample. Even if the solution sample leaks out to a region on the outsideof the pinching part 41, the bottomed fitting holes 11 provided in thebottom face 5 a of the depression 5 in the measurement board 3 canprevent the solution sample from leaking out of the depression 5. Whenbringing the pinching part 41 into contact with a predetermined part ofthe Raman spectroscopic analyzer 50 in the case of performing Ramanspectroscopic analysis (see FIG. 12), the pinching part 41 can beutilized as a spacer for placing a focal point of excitation light atthe optical function part 20.

In the SERS unit 1A, the measurement board 3 is provided with thedepression 9 containing a part of the SERS element 2 on the substrate 21side and restraining the SERS element 2 from moving in directionsperpendicular to the thickness direction of the substrate 21. This canposition the SERS element 2 with respect to the measurement board 3.This can also prevent the SERS element 2 from shifting from themeasurement board 3.

In the SERS unit 1A, the holding part 4 is formed separately from themeasurement board 3 and mechanically secured to the measurement board 3.This can simplify the structure of the measurement board 3. In addition,as compared with a case where the holding part 4 is secured to themeasurement board 3 with an adhesive, for example, the optical functionpart 20 can also be inhibited from deteriorating because of ingredientscontained in the adhesive.

In the SERS unit 1A, the measurement board 3 is formed integrally from aresin. This makes it harder for chipping to occur and thus can securelyinhibit the optical function part 20 from deteriorating because ofchipped pieces adhering thereto. Further, embossing the outer surface ofthe measurement board 3 or using a resin having a light-absorbing coloras a material for the measurement board 3 can inhibit stray light fromoccurring at the time of Raman spectroscopic analysis.

In the SERS unit 1A, the measurement board 3 is provided with aplurality of hollowed parts 8 so as to form the wall parts 6, 7extending in directions perpendicular to the thickness direction of themeasurement board 3. This prevents the measurement board 3 from warpingand thus can accurately place a focal point of excitation light at theoptical function part 20 when arranging the measurement board 3 on thestage 51 of the Raman spectroscopic analyzer 50 in the case where Ramanspectroscopic analysis is performed.

Modified examples of the SERS unit 1A will now be explained. Asillustrated in FIG. 7, the pinching part 41 of the holding part 4 may beformed so as to have a rectangular inner edge when seen in the thicknessdirection of the substrate 21. As illustrated in FIG. 7(a), the pinchingpart 41 may be formed such as to come into contact with the SERS element2 in the ring-shaped region of its inner edge. As illustrated in FIG.7(b), the pinching part 41 may be formed such as to come into contactwith the SERS element 2 in areas opposing each other in the ring-shapedregion of its inner edge. As illustrated in FIG. 7(c), the pinching part41 may be formed such as to come into contact with the SERS element 2 ata plurality of projections 41 b formed in its inner edge.

As illustrated in FIG. 8, the front face 41 a of the pinching part 41 ofthe holding part 4 may be located on the inside of the depression 5 withrespect to the bottom face 13 a of the widened part 13 of themeasurement board 3. In this case, the cover 12 is supported by themeasurement board 3 alone. As illustrated in FIG. 9, one of partsopposing each other in the ring-shaped pinching part 41 may be rotatablysupported by the measurement board 3, while the other is adapted toengage the measurement board 3. This structure makes it possible tomanage the measurement board 3 and holding part 4 in a state where theholding part 4 is attached to the measurement board 3. When assemblingthe SERS unit 1A, the holding part 4 can easily hold the SERS element 2by arranging the SERS element 2 in the depression 9 while the holdingpart 4 is open and then closing the holding part 4 so as to engage theother part of the pinching part 41 with the measurement board 3. Formaking it easier to open and close the holding part 4, a spring may beinstalled between the one part of the holding part 4 and the measurementboard 3.

Second Embodiment

As illustrated in FIGS. 10 and 11, a SERS unit 1B differs from theabove-mentioned SERS unit 1A mainly in that a plurality of pinchingparts 41 of the holding part 4 are arranged around the optical functionpart 20 of the SERS element 2. In the SERS unit 1B, the depression 9containing a part of the SERS element 2 on the substrate 21 side isprovided in the front face 3 a of the measurement board 3. The holdingpart 4 has a plurality of pinching parts 41 arranged around the opticalfunction part 20 of the SERS element 2 and leg parts 42 extending fromthe respective pinching parts 41 toward the rear face 3 b of themeasurement board 3. Fitting holes 11 are provided in the front face 3 aof the measurement board 3 so as to correspond to the respective legparts 42. The leg parts 42 are fitted into the respective fitting holes11 in a state where the pinching parts 41 are in contact with theconductor layer 23 of the SERS element 2.

In the SERS unit 1B, the holding part 4 holds the SERS element 2mechanically in the measurement board 3 as in the above-mentioned SERSunit 1A. Therefore, the SERS unit 1B can inhibit the optical functionpart 20 from deteriorating.

In the SERS unit 1B, the holding part 4 has the pinching part 41pinching the SERS element 2 in cooperation with the measurement board 3as in the above-mentioned SERS unit 1A. This can securely hold the SERSelement 2 in the measurement board 3. This can also prevent the moldedlayer 22 and conductor layer 23 formed on the substrate 21 in the SERSelement 2 from peeling from the substrate 21.

In the SERS unit 1B, a plurality of holding parts 41 are arranged aroundthe optical function part 20. This makes it possible to hold the SERSelement 2 stably in the measurement board 3. Further, as illustrated inFIG. 12, when setting the SERS unit 1B to a pressing mechanism 56 of theRaman spectroscopic analyzer 50 so as to bring the pinching parts 41into contact with a holder 57 of the Raman spectroscopic analyzer 50 inthe case of performing Raman spectroscopic analysis, the pinching parts41 can be utilized as spacers for placing a focal point of excitationlight at the optical function part 20. At this time, the contact parts41 also prevent the optical function part 20 from being damaged byphysical contact.

In the SERS unit 1B, the pinching parts 41 are rotatable around theircorresponding leg parts 42 with respect to the measurement board 3. As aconsequence, at a stage prior to assembling the SERS unit 1B, themeasurement board 3 and holing part 4 can be managed in a state wherethe holding part 4 is attached to the measurement board 3 while thepinching parts 41 are retracted from above the depression 9 of themeasurement board 3. When assembling the SERS unit 1B, arranging theSERS element 2 in the depression 9 and then rotating the pinching parts41 around the leg parts 42 enables the holding part 4 to hold the SERSelement 2 easily.

Modified examples of the SERS unit 1B will now be explained. Asillustrated in FIG. 13(a), guide grooves 15 for arranging the respectiveleg parts 42 of the holding part 4 may be provided in side faces of thedepression 9 formed in the measurement board 3. This structure enablesthe leg parts 42 to fit into the fitting holes 11 easily and securely.In this case, the leg parts 42 can also position the SERS element 2. Asillustrated in FIG. 13(b), the depression 9 can also position the SERSelement 2 in the case where the guide grooves 15 are provided.

As illustrated in FIG. 14(a), the SERS element 2 may be arranged in thefront face 3 a of the measurement board 3. That is, the lower face ofthe substrate 21 of the SERS element 2 may abut against the front face 3a of the measurement board 3. This structure can improve the strength ofthe measurement board 3 by the absence of the depression 9. Asillustrated in FIG. 14(b), the leg parts 42 of the holding part 4 may beformed with stoppers 42 a, respectively. In this structure, fitting theleg parts 42 into the fitting holes 11 until the stoppers 42 a come intocontact with the measurement board 3 enables the pinching parts 41 tocome into contact with the SERS element 2 and exert a substantiallyfixed pressure thereon, thereby preventing the pressure from acting morethan necessary on the SERS element 2.

As illustrated in FIG. 15, for restricting rotation areas of thepinching parts 41 when the pinching parts 41 are rotated around the legparts 42 with respect to the measurement board 3, the front face 3 a ofthe measurement board 3 may be provided with depressions 16. At a stageprior to assembling the SERS unit 1B, this structure enables thepinching parts 41 to be retracted from above the depression 9 of themeasurement board 3 to substantially fixed positions. Therefore, whenassembling the SERS unit 1B, an operation of rotating the pinching parts41 around the leg parts 42 so as to make the holding part 4 hold theSERS element 2 can be done efficiently.

As illustrated in FIG. 16, the holding part 4 may engage the measurementboard 3 such that the holding parts 41 can advance and retract withrespect to the SERS element 2 arranged in the depression 9. Asillustrated in FIG. 17, a plurality of pinching parts 41 may be arrangedsuch as to come into contact with the SERS element 2 in each of areasopposing each other in the ring-shaped region in the outer edge of theSERS element 2.

Third Embodiment

As illustrated in FIG. 18, a SERS unit 1C differs from theabove-mentioned SERS unit 1B mainly in that the holding part 4 is formedintegrally with the measurement board 3. When assembling the SERS unit1C, the holding part 4 is deformed such as to open each pinching part 41as illustrated in FIG. 18(a), so that the SERS element 2 is arranged onthe measurement board 3, and then the deformed holding part 4 isreturned to its original state so as to close each pinching part 41 asillustrated in FIG. 18(b), thereby causing the holding part 4 to holdthe SERS element 2.

In the SERS unit 1C constructed as in the foregoing, the holding part 4mechanically holds the SERS element 2 in the measurement board 3 as inthe above-mentioned SERS unit 1B. Therefore, the SERS unit 1C caninhibit the optical function part 20 from deteriorating.

In the SERS unit 1C, the holding part 4 has the pinching part 41pinching the SERS element 2 in cooperation with the measurement board 3as in the above-mentioned SERS unit 1B. This can hold the SERS element 2securely in the measurement board 3. This can also prevent the moldedlayer 22 and conductor layer 23 formed on the substrate 21 in the SERSelement 2 from peeling from the substrate 21.

In the SERS unit 1C, the holding part 4 is formed integrally with themeasurement board 3. This can reduce the number of components in thesurface-enhanced Raman scattering unit 1C. In addition, as compared withthe case where the holding part 4 is secured to the measurement board 3with an adhesive, for example, the optical function part 20 can be moreinhibited from deteriorating because of ingredients contained in theadhesive.

Modified examples of the SERS unit 1C will now be explained. Asillustrated in FIG. 19, each pinching part 41 may have a tilted surface41 c formed so as to widen toward the side opposite from the measurementboard 3. This structure can easily guide the SERS element 2 to itsholding position in the measurement board 3 when assembling the SERSunit 1C. This can also inhibit stray light from occurring at the time ofRaman spectroscopic analysis. As illustrated in FIG. 20, each pinchingpart 41 may have a tilted surface 41 d formed so as to widen toward themeasurement board 3. This structure can facilitate an operation ofdeforming the holding part 4 so as to open each pinching part 41 whenassembling the SERS unit 1C. As illustrated in FIG. 21, each pinchingpart 41 may have a cutout 41 e for engaging a jig 60 used for theoperation of deforming the holding part 4 so as to open each pinchingpart 41. This structure can facilitate the operation of deforming theholding part 4 so as to open each pinching part 41 by using the jig 60,while securely preventing the jig 60 from coming into contact with theoptical function part 20 when assembling the SERS unit 1C.

While the first to third embodiments of the present invention areexplained in the foregoing, the present invention is not limited to theabove-mentioned embodiments. For example, as illustrated in FIG. 22, aspring-shaped holding part 4 pinching the SERS element 2 in a directionparallel to the front face 3 a of the measurement board 3 may be formedintegrally with the measurement board 3 within the depression 9 forarranging the SERS element 2. This structure enables substantially thewhole area of the front face of the SERS element 2 to serve as theoptical function part 20.

As illustrated in FIG. 23, a plurality of SERS elements 2 may bearranged on the measurement board 3, while a holding part 4 having aplurality of openings 4 a corresponding to the respective opticalfunction parts 20 of the SERS element 2 is attached to the measurementboard 3. Thus constructed SERS unit 1D can efficiently perform Ramanspectroscopic analysis for a plurality of samples.

The material for the measurement board 3 is not limited to resins, butmay be low-melting glass, ceramics, and the like. The measurement board3 can be formed integrally from low-melting glass as from a resin. Froma ceramic, the measurement board 3 can be formed by firing, for example.Not only the above-mentioned materials and forms, but various materialsand forms can also be employed for the structures of the SERS units 1Ato 1D. The ring shape is not limited to circular rings, but encompassesother ring shapes such as rectangular rings.

The fine structure part 24 may be formed on the front face 21 a of thesubstrate 21 either indirectly with the support part 25, for example,interposed therebetween or directly. The conductor layer 23 is notlimited to the one directly formed on the fine structure part 24, butmay indirectly be formed on the fine structure part 24 through somelayers such as buffer metal (Ti, Cr, and the like) layers for improvingthe adhesion of the metal to the fine structure part 24.

INDUSTRIAL APPLICABILITY

The present invention can provide a surface-enhanced Raman scatteringunit which can inhibit the optical function part from deteriorating anda Raman spectroscopic analysis method using such a surface-enhancedRaman scattering unit.

REFERENCE SIGNS LIST

1A, 1B, 1C, 1D: SERS unit (surface-enhanced Raman scattering unit); 2:SERS element (surface-enhanced Raman scattering element); 3: measurementboard; 4: holding part; 6, 7: wall part; 8: hollowed part; 9:depression; 20: optical function part; 21: substrate; 41: pinching part.

The invention claimed is:
 1. A surface-enhanced Raman scattering unitcomprising: a surface-enhanced Raman scattering element having asubstrate and an optical function part formed on the substrate, theoptical function part for generating surface-enhanced Raman scattering;a measurement board supporting the surface-enhanced Raman scatteringelement upon measurement; and a holding part mechanically holding thesurface-enhanced Raman scattering element in the measurement board,wherein the holding part has a pinching part pinching thesurface-enhanced Raman scattering element in cooperation with themeasurement board, and wherein the pinching part is formed into a ringso as to surround the optical function part when seen in a thicknessdirection of the substrate.
 2. A surface-enhanced Raman scattering unitaccording to claim 1, wherein the measurement board is provided with adepression containing at least a part of the surface-enhanced Ramanscattering element on the substrate side and restraining thesurface-enhanced Raman scattering element from moving in a directionperpendicular to a thickness direction of the substrate.
 3. Asurface-enhanced Raman scattering unit according to claim 1, wherein theholding part is formed separately from the measurement board andmechanically secured to the measurement board.
 4. A surface-enhancedRaman scattering unit according to claim 1, wherein the holding part isformed integrally with the measurement board.
 5. A surface-enhancedRaman scattering unit according to claim 1, wherein the measurementboard is formed integrally from a resin.
 6. A surface-enhanced Ramanscattering unit according to claim 5, wherein the measurement board isprovided with a hollowed part so as to form a wall part extending in adirection perpendicular to a thickness direction of the measurementboard.
 7. A surface-enhanced Raman scattering unit according to claim 1,wherein the holding part pinches a side face of the surface-enhancedRaman scattering element.
 8. A Raman spectroscopic analysis methodcomprising: a first step of preparing the surface-enhanced Ramanscattering unit according to claim 1 and arranging a sample on theoptical function part; and a second step, after the first step, ofsetting the surface-enhanced Raman scattering unit to a Ramanspectroscopic analyzer, irradiating the sample arranged on the opticalfunction part with excitation light, and detecting Raman-scattered lightderived from the sample, so as to perform Raman spectroscopic analysis.